1. Field of the Invention
The present invention relates to a portable terminal. More particularly, the present invention relates to a letter input method and apparatus of the portable terminal supporting a virtual keypad having a plurality of character keys.
2. Description of the Related Art
With the advance of data communication and semiconductor technologies, the use of portable terminals is widespread and the number of users is increasing rapidly. Recently, the portable terminals are evolving into multifunctional devices integrating various functions in line with the mobile convergence tendency. As a representative case, a recent mobile communication terminal integrates various multimedia functions including a Television (TV) function such as Digital Multimedia Broadcasting (DMB) and Digital Video Broadcasting (DVB), a music player function (e.g., Motion Picture Experts Group (MPEG) Audio Layer-3 (MP3)), a camera function, an Internet function, and an electronic dictionary function, as well as conventional communication functions such as voice and message communication.
Recently developed portable terminals are being equipped with a touchscreen due largely to its input convenience. Typically, touchscreen-enabled portable terminals are not provided with a 3×4 button keypad of the related art. The keypad is provided instead on the touchscreen display of the portable terminal in the form of a virtual keypad. However, due to the space-constrained display, each key is assigned multiple letters (e.g., 3 letters) that are selected according to a number of input touches made thereon. For example, if a touch is made on the key assigned the three letters of ‘a,’ ‘b,’ and ‘c’, the letter ‘a’ is first displayed on the screen, and when the touch is made repeatedly, the displayed letter changes to ‘b’ and then ‘c’. Accordingly, in order to input the letter ‘c’, the user must touch the key at least three times in a brief time period. That is, the letter input method of the related art of a 3×4 button keypad has a drawback in that multiple touches must be made to a key to input a letter. Particularly, when the user inputs a series of letters that each require multiple touches, the total number of touches required increases severalfold, resulting in user inconvenience.